The present invention relates to material unloading devices and more particularly relates to devices of the type including a variable-speed unloading conveyor and a distributing unit.
Material unloaders such as manure spreaders commonly include a box or the like having a conveyor to move material at various selected rates to the rear of the box to the distributing unit or beaters. The conveyor and the distributing unit are often powered by the same drive source which, in the case of a towed device, usually is the power takeoff shaft of a tractor.
The above-mentioned material unloaders normally employ a ratchet wheel and pawl mechanism, a worm gear drive or various multiple clutch arrangements or the like to drive the conveyor at selectively variable speeds. Since a ratchet wheel and pawl mechanism is easy to shift, a rope control often is used to vary the conveyor drive speed. However, such a mechanism is relatively complex and includes intermittently operating parts subject to considerable wear. The worm gear or multiple clutch drive arrangements, although possessing several advantages over the ratchet and pawl system, usually have to be shifted while under load and therefore a rope control is difficult for the operator to manipulate properly from his position on the tractor seat. Often the rope control requires much effort to operate or is too easily movable to an undesired setting, giving the wrong combination of unloader conveyor speed and distributing unit operation. Some of the units have one control for the beaters and another for the conveyor adding to the difficulty. Additionally, the various arrangements generally do not provide a sufficient range of conveyor speeds, especially a very high conveyor speed to quickly clean out the box. In cold weather the box can freeze up if not cleaned promptly, locking the conveyor and preventing use of the unloader. Because of the relatively slow conveyor clean-out speed, the operator commonly will not wait the necessary time to achieve an adequate cleaning.